No doubt as long as man and all other animals are viewed as independent creations, an effectual stop is put to our natural desire to investigate as far as possible the causes of Expression.

We are to admit no more causes of natural things than such as are both true and sufficient to explain their appearances.

That there is much suffering in the world no one disputes. Which is more likely, that pain and evil are the result of an all-powerful and good God, or the product of uncaring natural forces? The presence of much suffering agrees well with the view that all organic beings have been developed through variation and natural selection.

The natural history of this archipelago is very remarkable; it seems to be a little world within itself.

Natural science will in time incorporate into itself the science of man, just as the science of man will incorporate into itself natural science: there will be one science.

Darwin's book is very important and serves me as a basis in natural science for the class struggle in history. One has to put up with the crude English method of development, of course. Despite all deficiencies not only is the death-blow dealt here for the first time to 'teleology' in the natural sciences, but their rational meaning is empirically explained.